Swirl Technology: Enhancement of Design, Evaluation, and Application

Abstract

While different forms of swirl and vortex technologies have been developed during the last thirty years, their major function has been the dual purpose of flow regulation and settleable-solids concentration for combined sewer overflows. A variety of opinions have developed regarding the application of these technologies, which vary from overwhelming support to reservations of their effectiveness. Performance of swirl/vortex devices depends on the settling characteristics of the suspended solids and the fraction of dissolved solids in the storm flow. When correctly installed with other controls of the combined-sewerage or separately sewered storm-water system, swirl/vortex devices can play an important role in combined sewer overflow and storm-water discharge pollution control. Reliable determination of performance depends principally upon accurate sampling techniques, suspended solids and other pollutant analyses, and settling-velocity distribution of the influent and effluent. Simultaneous flow-rate measurement synchronized to sampling times is also necessary. This paper discusses design, evaluation, and application practice enhancements for the use of swirl/vortex technologies as part of a combined sewer overflow and storm-water pollution control system.